Trochoid type of rotary piston combustion engine

ABSTRACT

A rotary piston combustion engine of the trochoid type. The engine includes a housing including a shell with multiarcuate interior surface and end pieces. The housing is traversed by an eccentric assembly including an eccentric shaft with an eccentric thereon. An oil cooled piston is provided bearing axial gas seals sliding along the end walls of the housing and being rotatably mounted on the eccentric of the eccentric shaft. At least one oil seal is provided between the piston and the eccentric assembly. The oil seal is pressed tightly against its matching surface under the action of a compressed gas passing from a working chamber by way of the axial gas seals. A sealing ring is set in the respective face of the piston and encloses the oil seals and is in sealing contact with the adjoining end wall of the housing. The sealing ring is spanned by a passage extending from a region of the adjacent end wall of the housing radially internal to the inner envelope curve of the axial gas seals and radially external to the outer envelope curve of the sealing ring. The passage is fitted with a check valve that clears the passage only when a higher pressure prevails radially outside the sealing ring than radially within the same.

United States Patent [191 Gutbrod 'Oct. 16, 1973 TROCHOID TYPE OF ROTARY PISTON COMBUSTION ENGINE [75] Inventor: Willi Gutbrod, Heinsheim, Germany [73] Assignees: Audi Nsu Auto Union Aktiengesellschaft, Neckarsulm; Wankel Gmbl-l, Lindau/Bodensee, both of Germany 22 Filed: Mar. 23, 1972 21 Appl. No.: 237,479

[52] US. Cl .1 418/91, 418/104, 418/142 Primary Examiner-Carlton R. Croyle Assistant Examiner-John J. Vrablik AltorneyDavid S. Kane et al.

57 ABSTRACT A rotary piston combustion engine of the trochoid type. The engine includes a housing including a shell with multiarcuate interior surface and end pieces. The housing is traversed by an eccentric assembly including an eccentric shaft with an eccentric thereon. An oil cooled piston is provided bearing axial gas seals sliding along the end walls of the housing and being rotatably mounted on the eccentric of the eccentric shaft. At least one oil seal is provided between the piston and the eccentric assembly. The oil seal is-pressedtightly against its matching surface under the action of a compressed gas passing from a working chamber by way of the axial gas seals. A sealing ring is set in the respective face of the piston and encloses the oil seals and is in sealing contact with the adjoining end wall of the housing. The sealing ring is spanned by a passage extending from a region of the adjacent end wall of the housing radially internal to the inner envelope curve of the axial gas seals and radially external to the outer envelope curve of the sealing ring. The passage is'fitted with a check valve that clears the passage only when a higher pressure prevails radially outside the sealing ring than radially within the same.

2 Claims, 3 Drawing Figures mnnmnu 16 1975 3.765806 SHEET 2 UP 2 TROCI-IOID TYPE OF ROTARY PISTON COMBUSTION ENGINE BACKGROUND OF THE INVENTION The invention relates to a rotary piston combustion engine having a housing composed of a shell with multiarcuate interior surface and end pieces traversed by an eccentric shaft. An oil cooled piston bearing axial gas seals sliding along the end walls of the housing is rotatably mounted on the eccentric of the eccentric shaft. At least one oil seal is provided between the piston and the eccentric or a part revolving with it. This oil seal is pressed tightly against its matching surface under the action of a compressed gas passing from a working chamber by way of the axial gas seals. A sealing ring set into the face of the piston encloses the oil seal and is in sealing contact with the adjoining end wall of the housing. This latter sealing ring has the function of preventing passage of cooling oil into the working chant:

bers when the engine is not running, since the oil seal will not work in the absence of gas pressure. In order for the gas pressure to be able to act on the oil seal when the machine is running, the sealing ring may be so fashioned that it will be lifted away from the end wall of the housing by the pressure of the compressed gas. This construction of the sealing ring involves difficulties of design. It has therefore been proposed that a passage be provided in the end wall on which the sealing ring slides, to be periodically passed over by the sealing ring when the engine is running and thereby permit access of the compressed gas to the oil seal. This passage is so arranged that when the engine is not running, no oil can enter the working chambers through the passage.

It has been found that in some operating conditions, a negative pressure prevails in the space radially external to the sealing ring. Particularly in the phase when the engine is at rest, the result is that oil leakage having escaped from the interior of the piston by way of the oil seal will be aspirated by said passage and enter the working chambers. The consequence of this is increased oil consumption and exhaust smudge especially when starting.

SUMMARY OF THE INVENTION The object of the invention is to avoid the disadvantages outlined. For this purpose, it is proposed that the sealing ring be spanned by a passage extending from a region of the adjoining housing end wall radially internal to the internal envelope curve of the axial gas seals and radially external to the external envelope curve of the sealing ring. The passage opens into the space radially intemal to the sealing ring and is fitted with a check valve that clears the passage when the pressure in the space between the axial gas seals and the sealing ring is higher than the pressure in the space radially internal to the sealing ring.

The proposal of the invention securely prevents oil from passing out of the space radially internal to the sealing ring into the working chambers. Furthermore,

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1.

it affords supply of compressed gas to the space radially DESCRIPTION OF THE PREFERRED EMBODIMENT The rotary piston combustion engine has a housing 1 composed of a shell 2 with biarcuate interior surface 3 tric shaft 5 is mounted in the end pieces 4. An oil cooled triangular piston 7 is rotatably arranged on the eccentric 6 of eccentric shaft 5. The piston 7 has interior spaces 8 through which the cooling oil flows. The piston 7 is provided at its vertices with radial seals 25 and on its faces 9 with axial gas seals consisting of sealing strips 10 and sealing pins 11 and pressed against the adjoining end wall 12 of the housing by springs. In this way, three working chambers 13 sealed off from each other are formed.

To prevent cooling oil from passing out of the piston chambers 8 into the working chambers 13, preferably on each side of the piston, anoil seal 14 acting between the piston 7 and the eccentric 6 is provided. In the depicted embodiment, the oil seal takes the form of an externally tensing slit piston ring with gas tight butt arranged in a groove 15 of a disc 16 rotationally fixed to the eccentric. The oil seal 14 is operative only when compressed gas passing by way of axial gas seals 10 and 11 into the space 17 is holding it against the wall of groove 15 towards the piston chamber 8. To prevent passage of cooling oil out of piston chamber 8 into working chambers 13 when the engine is at rest and the gas pressure is not present, a closed sealing ring 18 is provided in the face 9 of the piston, and is held by a spring 19 against the end wall 12 of the housing. This sealing ring 18 is spanned by a passage 29 extending from a region 21 of the end wall 12 of the housing radially internal to the internal envelope curve 22 of the axial gas seals 10 and 11 and radially external to the external envelope curve 23 of the sealing ring 18. Region 21, shown shaded in FIG. 2, occurs twice on each end wall of an engine housing having an interior shell surface 3 in the shape of a biarcuate epitrochoid, so that the passage 20 may extend from either or both of the regions 21. Thus through the passage 20, compressed gas having escaped from the working chambers by way of the axial gas seals 10 and 11 can enter the space 17. To prevent oil from being aspirated out of chamber 17 into any of the working chambers'l3 when a lower pressure prevails in the space radially external to the sealing ring 18 than in the space 17, a spring loaded check valve 24 is arranged in the passage 20.

The arrangement shown in,FIG. 3 for the left hand side of the piston may of course by provided for the right hand side of the piston as well.

I claim:

3 4 l. A rotary piston combustion engine of trochoid wall of the piston and enclosing the oil seal and in type comprising: sealing contact with the adjacent end wall of the a housing including a shell with multiarcuate interior h i surface and end walls, said housing being traversed a passage extending f a region f the adjacent end by an eccemfic assembly including an eccentric 5 wall of the housingradially internal to the inner enshaft with an eccentric thereon; an oil cooled piston bearing axial gas seals sliding along the end walls of the housing being rotatably mounted on the eccentric of the eccentric shaft to form gas working chambers in the housing; at least one oil seal being provided between the piston and the eccentric assembly;

velope curve of the axial gas seals and radially external to the outer envelope curve of the sealing ring and extending to communicate with the space between the oil seal and the housing end wall; and a check valve in the passage that clears the passage only when a higher pressure prevails radially outthe oil seal being pressed tightly against an end wall Side the l g ring than ly Within the f the piston d against the Centric assembly 2. The invention in accordance with claim 1 wherein under the action 0f a compressed gas pa sin fro the at least one Oil seal is provided between the piston 21 working chamber by way of said axial gas seals; and a part revolving with the eccentric. a sealing ring being set in the end face of said end 

1. A rotary piston combustion engine of trochoid type comprising: a housing including a shell with multiarcuate interior surface and end walls, said housing being traversed by an eccentric assembly including an eccentric shaft with an eccentric thereon; an oil cooled piston bearing axial gas seals sliding along the end walls of the housing being rotatably mounted on the eccentric of the eccentric shaft to form gas working chambers in the housing; at least one oil seal being provided between the piston and the eccentric assembly; the oil seal being pressed tightly against an end wall of the piston and against the eccentric assembly under the action of a compressed gas passing from a working chamber by way of said axial gas seals; a sealing ring being set in the end face of said end wall of the piston and enclosing the oil seal and in sealing contact with the adjacent end wall of the housing; a passage extending from a region of the adjacent end wall of the housing radially internal to the inner envelope curve of the axial gas seals and radially external to the outer envelope curve of the sealing ring and extending to communicate with the space between the oil seal and the housing end wall; and a check valve in the passage that clears the passage only when a higher pressure prevails radially outside the sealing ring than radially within the same.
 2. The invention in accordance with claim 1 wherein the at least one oil seal is provided between the piston and a part revolving with the eccentric. 